Your Definitive Guide to Buying Lumber – with Dunn Lumber
Quality lumber can make or break the success of your construction projects. But without years of experience using lumber, knowing what grade or species is best for you can be tough to figure out. Industry expertise can make all the difference, and there’s no better experts in lumber than Dunn Lumber. We’ve applied more than a century’s worth of experience to the following lumber buying guide so that you have another top-quality tool at your disposal.
You’ll find helpful information about how lumber is distinguished as well as the benefits of specific wood species or grades. Finally, we’ve shared some of the most common questions other professionals have about a few of our key products.
LUMBER BUYING GUIDE PART I
Identifying Different Types of Lumber
Lumber is distinguished by a number of traits. Lumber can be identified from the source species of tree. Other lumber characteristics are a result of industrial treatments and manufacturing techniques. Knowing the differences between types of lumber will make the buying process easier.
When choosing lumber for your next project, consider:
Measurements: The size and dimension of each piece of lumber can vary depending on the complexity of your project.
Composition: The composition of your lumber is the biggest influence on its internal strength, density and other key advantages of wood. The age and species of the tree will also influence these traits. For contractors and builders in Wisconsin, SPF lumber such as spruce is common.
Appearance: The color and appearance of wood varies greatly between different species. Colors can range from whites and yellows to reds and browns. Each type of tree has a unique woodgrain pattern as well, which affects visual appeal and can even influence the wood’s strength.
Treatments: Chemical or mechanical treatments can improve existing qualities of lumber. These treatments bring out natural colors or create a weather-resistant coating. Treated lumber is ideal for outdoor projects that see heavy use or changing Midwestern weather.
Dimensional lumber consists of boards cut into predetermined sizes and shapes. When you think of lumber, you’re probably imagining a piece of dimensional lumber.
Standardized measurements are extremely cost effective and a necessary time-saver for construction projects. These boards are extremely versatile and one of the most popular types of lumber in the industry, used for projects such as:
House framing: By far the most popular use for dimensional lumber. Standard board measurements help streamline construction and ensure structural integrity. Quality dimensional lumber should always be strong enough to support multifamily house frames.
Cabinets and Furniture: Cabinets, dressers and other storage is another common use of dimensional lumber. The right custom cabinets can turn your kitchen or bathroom into a beautiful, one-of-a-kind space.
Flooring: Dimensional lumber is even a good choice for indoor flooring. Hardwood is generally best, but dimensional hardwood may have to be special ordered. This type of dimensional lumber can even be installed on the ceiling or as wall paneling.
When buying dimensional lumber, don’t forget that there are “nominal” dimension sizes and “actual” dimension sizes. Pieces of dimensional lumber can have several actual sizes grouped under the same nominal sizing.
- Nominal sizes: This refers to the intended dimensions of the lumber before it is surfaced (also called planed) smooth on all four sides. The standard 2” x 4” piece of lumber is a common nominal size.
- Actual sizes: These are the final, exact measurements of each piece of lumber. If a board has a nominal size of 2” x 4”, the actual size is typically 1-1/2” × 3-1/2”.
If that seems confusing, just think of nominal sizes as the different groups dimensional lumber is placed into, while the actual sizes are specific measurements of each piece.
SPF Lumber – A North American Standard
SPF (Spruce-Pine-Fir) refers to dimensional lumber from the North American conifers of spruce, pine and fir. SPF lumber is prized for its lightweight, yet strong composition, providing lots of structural stability. SPF’s consistently high grade makes it a fantastic option for constructing both homes and commercial buildings.
SPF lumber is common in the Midwest, and is often sourced from forests in Minnesota, Michigan and Wisconsin. You’ll be able to spot SPF lumber with its clear “SPF” markings on each piece’s grading stamp. In fact, the grading stamp is a great place to find all sorts of key information about each piece of lumber, such as:
- Species: Wood sourced from spruce, pine and fir will be marked SPF. The strength and versatility of these species is why SPF has such a consistent reputation.
- Grade: Lumber is graded in a variety of ways. This part of the stamp will inform you of what kind of projects each piece of lumber is suited for. You’ll see terms like “Select” or “Structural,” as well as numbers #1, #2 or #3.
- Moisture Content: This is determined at the mill where the lumber is graded. In the Midwest, you’ll mostly likely find moisture content between 15% to 20%. Mills use different terms for the moisture levels, including:
- S-GRN: Surfaced green, for lumber with a moisture content higher than 19%. It may also be labeled as “AD” for air-dried.
- S-DRY: Surfaced dry lumber should have a moisture content lower than 19%.
- KD: Kiln-dried wood is useful in humid climates, where excessive moisture is much more likely to affect the lumber with rot or mold growth. Most of Dunn Lumber’s lumber is kiln-dried to suit Midwestern climates.
- MC-15: Lumber with moisture content at 15% or lower will be labeled this way.
- Grading Certification: The certification comes from the relevant association or authority responsible for making sure the lumber was graded accurately.
- Mill of Origin: This part of the stamp will reveal what mill the lumber was processed at. Some stamps include the mill’s name or trademark.
People without experience in wood products may assume lumber and timber are the same thing. Timber wood refers to whether the wood has been harvested or processed. Canadian and US markets use the term “timber” to refer to unharvested wood. But in the UK, Australia and New Zealand, “timber” refers to sawn wood instead.
As long as it hasn’t been harvested, both living and felled trees are considered timber. Professionals will instead distinguish timber by whether it’s softwood or hardwood, which depends on the species of tree. The terms hard and soft don’t refer to the wood’s actual toughness.
Hardwoods are deciduous trees like oak and maple. These trees grow more slowly and lose their leaves during the fall. A slower growth rate makes hardwood denser compared to softwood. This also creates attractive wood grains and other interesting visual elements.
In construction, hardwood is used for walls, ceiling and floors. When looking for quality hardwoods in the Midwest, red oak, maple, poplar and ash are strong choices.
There are some other industry terms you may encounter when comparing hardwoods: S2S, S3S and S4S. As hardwood is processed, one or more sides will be surfaced. The number in each label is for how many sides of a piece of lumber have been surfaced. Dunn Lumber can help you decide between hardwoods, especially if you’re unsure of how many sides should be surfaced for your project.
S2S lumber has only been surfaced on the face sides, which are broad and flat.
S3S lumber features a single-surfaced edge side while the other is ripped straight.
S4S lumber is surfaced on both face sides and both edge sides. S4S boards are the flat, parallel pieces of lumber you are most likely to find in lumber yards and hardware stores.
If all four sides are left unsurfaced, the lumber is called “rough-sawn.” You’ll have to mill it yourself to process rough-sawn wood into usable dimensions. Some woodworkers prefer rough-sawn lumber because they can mill it into the exact dimensions they need for a project.
The last term you may see when working with hardwoods is board foot. This is how hardwood is priced. Each board foot refers to a volume of one-twelfth of a cubic foot, or 12” by 12” by 1”. If you know the board feet measurements of the lumber you need, you’ll be able to get a rough estimate of the total cost.
Softwood trees include coniferous evergreens like pine, spruce and fir. These species are common in cooler climates and can be found in the forests of Minnesota and Michigan as well as Canada.
Their faster rate of growth creates a straighter woodgrain, which in turn means a higher strength-to-weight ratio. Softwood is processed into the bulk of timber products because of its cost-effectiveness.
Some wood products are treated or sent through manufacturing. Even though they’re now part of a composite material, a few treated products may still be referred to as timber. The term engineered instead refers to how the wood meets design specifications.
Structural panels: This includes plywood as well as fiber products like OSB (oriented strand board) and MDF (medium-density fiberboard) wood. Plywood is different from other engineered wood products because it is formed from sheets of wood, not smaller fibers or particles.
Mass timber: Large pieces of strong timber are still used in construction. Mass timber can mean the timber framing on homes as well as structural elements like joists, beams and trusses. Quality mass timber is a useful alternative to concrete and even steel in terms of strength. In particular, Douglas fir and cedar are increasingly prized for timbers.
Cross-laminated timber: Cross-laminated timber (CLT) wood is made from multiple layers of lumber cut from the same log. These layers are often placed perpendicular to each cut’s woodgrain. This improves structural integrity equally in all directions.
Manufactured Boards and Panels – OSB and Plywood
Plywood and oriented strand board (OSB) are popular engineered wood products. While they both come in sheets or panels, their manufacturing processes are very different.
OSB panels are made from large amounts of wood shavings, usually from trees otherwise unsuitable for lumber. These strands are mixed with resin adhesives before being pressed together into layers. The orientation of each layer is chosen according to the maximum strength.
Plywood is made from multiple thin layers of wood pressed together with glue. While the exterior can be hardwood, interior layers are generally from softwoods. While not as flexible as OSB, this rigidity is well-suited for projects that need to remain firmly in place.
Choosing Quality Plywood
Because plywood is built from multiple thin layers, only the outermost layer is fully visible. Core layers can vary in quality, with different thicknesses or moisture content. To tell the difference between high- and low-quality plywood, look for the following:
Strong exterior layers: The outermost layer is also known as the face veneer. Premium veneer features an even woodgrain that may look mirrored. Also known as bookmatched veneer, these layers are a sign of high-quality plywood.
Even thickness and straight lines: Some warping is common in plywood sheets. Look down one of the edges to see how straight it is. Uneven thickness is also more likely to affect a piece of plywood’s structural integrity.
Certified vendors and clear grading: Plywood can come in a variety of grades, but these aren’t always standardized across the industry.
In general, more plies per piece of plywood yields a stronger final product. One of the most common varieties is 3-ply, perfect for indoor projects that require greater aesthetic value. There is also 5-ply, which is more versatile and can be used both outdoors and indoors.
In addition, multi-ply, an umbrella term for any plywood with 7 or more layers. These are durable sheets strong enough for exterior and even structural projects.
When you use high-quality plywood, you’re working with an incredibly versatile building material. Plywood can be used for both structural and nonstructural projects. It’s often installed as subflooring or sheathing walls, floors and roofing. Hardwood plywood can be used for furniture manufacturing.
Medium-density fiberboard (MDF) is another engineered wood product. Like OSB, it’s made from smaller pieces of wood stuck together with adhesive resin. But these pieces are made up of smaller fibers and even sawdust, which makes a smoother product that is less likely to splinter or warp.
There are advantages and drawbacks to working with MDF lumber, such as:
- More affordable to work with: MDF is less expensive than both plywood and OSB. For budget-friendly projects, MDF lumber is a good option.
- Easier to cut and finish: Because MDF lacks woodgrain, cutting is fast and can be done in any direction. MDF is also much easier to paint.
- Poor resistance to water: MDF lumber is not water-resistant. As it starts to absorb water, MDF panels may begin to crumble. Other engineered wood products like plywood or OSB should be used for exterior projects.
- Off-gassing: MDF board is manufactured with formaldehyde adhesives. Over time, this adhesive can “off-gas” into the surrounding air. In 2010, the United States passed the Formaldehyde Standards for Composite Wood Products Act, which capped the concentration of these adhesives in MDF to a maximum of .11 ppm (parts per million).
According to the EPA, any MDF board or composite wood products manufactured after March 22, 2019, must be labeled TSCA Title VI compliant and meet their required emission standards.
Lumber for Decking
Outdoor decking is a popular project for any budget. They’re great spaces for relaxing or entertaining and can add value to a home. A wood deck is a classic option, but not your only one.
Popular materials for decking include:
- Treated wood: For wood decks, treated lumber is the most common option. Chemical treatments extend the life span of outdoor decks and protect it from moisture and insects. Treated wood is popular because it’s such a cost-effective
- Cedar: Cedar naturally resists rot and insect infestation, making it a premium option for decking among natural woods. These traits make cedar a more expensive option than treated wood, but still more affordable than composite materials.
- Composite: Made up of wood fibers and plastic, a binding agent makes composite decking denser and stronger than natural wood. It’s also extremely durable and nearly maintenance-free, which makes this type of decking cost efficient long-term. Installation costs will be higher than natural woods like treated lumber or cedar.
- Vinyl: Vinyl decking is manufactured from petroleum. Unlike other decking materials, it’s made entirely from non-wood material. A unique benefit of vinyl decking is the versatile manufacturing process, which can be fine-tuned so that vinyl decking resembles lumber’s color and woodgrain.
There are also several options for finishing your deck, including paint, stain and sealant. Which finish is best for you depends on the material you chose for the decking. For example, wood decks need to be refinished with quality stain or paint to keep looking their best. Composite decks, however, can’t be painted, making it a less than ideal for homeowners wanting to refresh the look of their decking every now and then.
Paint covers the wood grain and other natural qualities in exchange for stronger color. Stain is usually more transparent and provides a small degree of water-resistance. Sealant highlights the wood’s natural color and forms a protective coating to keep moisture out.
We first mentioned veneer when sharing tips for finding quality plywood. But wood veneer is an important part of many other projects with a wide range of materials.
A wood veneer is a thin cut of wood placed on both sides of core layers. This strengthens the wood and prevents expansion or splitting along the woodgrain. Common uses for wood veneers include wall paneling, flooring, exterior doors and kitchen cabinets. These projects rely on veneer’s natural stability as well as resistance to warping and splitting.
Some people assume veneers are a sign of low quality, but this is partly because its often confused with laminate. Laminate materials look similar to wood veneer but are actually made from plastic or even foil. The wood-grain pattern is printed on laminate, which often fades near the edges.
LUMBER BUYING GUIDE PART II
Evaluating Lumber Quality by Grade
In the United States, grading lumber helps ensure consistent quality for both hardwoods and softwoods as well as engineered wood products. Accurate grading should take natural properties into account as well as the estimated cost and waste associated with manufacturing each grade of wood. Dunn Lumber prides itself on offering a large supply of #2 highline SPF-sourced lumber for straight cuts and consistent quality.
One of the most important elements of grading is for the type of project. If lumber will experience load bearing or other stressors, it is categorized as structural lumber. When strength isn’t a big concern, the grading instead highlights visual elements like color and woodgrain. This is appearance lumber, sometimes referred to as board lumber.
Because hardwoods and softwoods feature different strengths, they’re graded separately. Make sure you are paying attention to both the type of wood as well as how it has been graded.
Structural Lumber – Rough Construction
Structural lumber grading is used for dimensional lumber and construction projects. The grading system is also used for timber framing. These are more likely to be softwoods because of the higher strength-to-weight ratio.
Structural lumber can also be categorized by stressed and non-stressed grades. Non-stressed structural lumber is commonly used for siding, shelving or subflooring. It’s used anywhere where visibility and a high degree of structural integrity is required. Beams, posts, joists, rafters and studs are just a few uses for stress-graded structural lumber.
Construction lumber should clearly display its grade stamp with information about the species, moisture content and other traits. Standardizing dimensional lumber makes grading structural lumber more consistent.
Appearance Lumber – Decorative Purposes
Appearance-grade lumber should have little to no imperfections such as knots or sap wood. The fewer imperfections, the higher grade of lumber. Hardwood is commonly graded this way because of its attractive colors and woodgrain. Softwoods are also graded for appearance, but with a different scale than structural-graded softwood.
Furniture-Grade – Equally Sturdy and Elegant
Furniture-grade wood is attractive and long lasting, making hardwood the most popular choice. For hidden parts of wooden furniture, engineered wood products like MDF lumber or plywood help keep costs down. They can be stronger than natural wood, which is useful for furniture that supports weight like chairs or storage.
Because softwoods are graded for both structural and appearance lumber, you should make sure you’re looking at appearance-grade softwood for furniture. You won’t need the degree of strength found in structurally graded lumber.
LUMBER BUYING GUIDE PART III
Finding Lumber Ideal for Your Project
The variety of woods, composite materials, grading systems and treatments can make finding the right lumber for your next project tedious and time-consuming. To help you along, Dunn Lumber has compiled a few of the most common comparisons between wood products. We’ve also included a few frequently asked questions about terms and products you may still be unsure of.
Treated Lumber vs. Cedar
For both homes and commercial properties, many owners prefer a natural wood deck. It’s made with treated lumber and offer a classic, timeless style. But treated wood decks need to be cleaned and maintained to keep them resistant to decay and weathering.
Cedar naturally resists rots, insects and other problems. While more expensive than treated lumber, investing in cedar is ideal for people who don’t have as much time for maintenance.
Treated Lumber vs. Composite Decking
Instead of treated lumber, some people use composite decking materials. Composite decking costs more but needs much less maintenance than treated lumber decks. When kept in good condition, a composite deck can last for decades.
Some people find the material too artificial, but newer versions of composite decking offer a more natural wooden appearance. Additionally, composite decking can’t be painted.
Ground Contact vs. Above-Ground Treated Lumber
Lumber used for exterior projects is graded based on dynamic conditions like the temperature and moisture levels. These environmental factors influence how long a piece of lumber is expected to last.
Treated lumber is graded for above-ground projects as well as ground contact. Ground contact lumber receives more chemical treatments designed to resist rot and decay. In fact, ground contact lumber can even be placed underground or in water. Above-ground lumber may be more cost-effective in dry or arid climates, but here in the Midwest, humidity is expected.
Treated wood columns are common in the Midwest, especially for house/shop combos that need a high level of structural strength as well as moisture resistance.
1 vs. 2 Pressure-Treated Lumber
Structural, pressure-treated lumber focuses on strength. Any structural lumber thicker than 2” should be graded this way.
#1 graded lumber is stronger and features fewer imperfections like knots. You’ll find #1 graded lumber when both strength and appearance are considered important.
#2 graded lumber is generally just as strong as #1, but visual flaws make it better suited for non-appearance projects like subflooring.
Hardwood vs Softwood
Hardwoods and softwoods are each made up of different species with their own strengths and weaknesses. But there are some key differences between hardwoods and softwoods that can help make choosing one or the other a little easier.
Softwoods are coniferous evergreens like spruce, fir, pine and juniper. These trees grow more quickly, resulting in a straighter woodgrain pattern and a shorter time to grow and process softwood lumber. The faster rate of growth often makes it less dense and a lighter weight than hardwood.
Hardwoods come from deciduous species like oak and birch. These slow-growing woods feature more complex woodgrains, making them well-suited for furniture making and other projects where visuals are important.
Other Commonly Asked Questions about Lumber
What is common wood?
You might see the term “common” wood on many different products. It’s also used online and in printed information about lumber. In general, common refers to affordable softwoods of average quality and appearance.
But within the industry, it’s a standard grade for lumber with knots. This lumber is frequently sourced from pine.
What is select wood?
The select grade is a step above common lumber. When lumber is considered select, it typically features little to no defects. This creates a crisp, natural appearance great for hardwood floors or softwood appearance lumber projects like cabinetry.
Is there a difference between dimensional lumber and studs?
Dimensional lumber and studs are both considered structural lumber. They’re also both cut in predetermined, standardized sizes. This leads to some confusion about whether dimensional lumber is any different than studs.
Stud-grade lumber is technically the same as dimensional. The grading for studs is instead because it’s restricted to bearing vertical loads like walls. Other dimensional lumber may be used for framing houses, flooring and ceilings, furniture and more.
Find the Right Lumber and Building Materials at Your Local Dunn Lumber
For contractors, builders and do-it-yourselfers in Wisconsin, Dunn Lumber is dedicated to making sure your next project succeeds. We work with the top brands and offer the highest-quality materials that meet our uncompromising standards.
To request a free estimate or expert advice, visit or contact Dunn Lumber.